Distributorless Direct Ignition Systems Overview

Eliminating the distributor improved reliability by reducing the number of mechanical components. Other advantages are:

• Greater control over ignition spark generation - There is more time for the coil to build a sufficient magnetic field necessary to produce a spark that will ignite the air/fuel mixture. This reduces the number of cylinder misfires.

• Electrical interference from the distributor is eliminated - Ignition coils can be placed on or near the spark plugs. This helps eliminate electrical interference and improve reliability.

• Ignition timing can be controlled over a wider range - In a distributor, if too much advance is applied the secondary voltage would be directed to the wrong cylinder.

All of the above reduces the chances of cylinder misfires and consequently, exhaust emissions.

Distributorless Ignition System

Igniter Ignition Coils

Igniter Ignition Coils

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Distributorless Ignition systems are usually defined as having one ignition coil with two spark plug wires for two cylinders. Distributorless Ignition Systems use a method called simultaneous ignition (also called waste spark) where an ignition spark is generated from one ignition coil for two cylinders simultaneously.

Direct Ignition Systems (DIS) have the ignition coil mounted on the spark plug. DIS can come in two forms:

• Independent ignition - one coil per cylinder.

Simultaneous ignition - one coil for two cylinders. In this system an ignition coil is mounted directly to one spark plug and a high tension cord is connected to the other spark plug. A spark is generated in both cylinders simultaneously.

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